1. Field of the Invention
The present invention relates to polymer, elastomer, or ceramic materials or composite materials employing polymers, elastomers, or ceramics as their matrix. More specifically, the present invention relates to the use of metallic nanostrands to form polymers, elastomers, ceramics, or composite materials with enhanced electrical conductivity.
2. Description of Related Art
Polymeric materials, either alone or reinforced with powders or fibers, are an attractive engineering material with respect to cost, weight, manufacturability and many other advantages. However, with the exception of some intrinsically conducting polymers, polymers generally possess poor electrical conductivity.
There are many conventional methods by which conductivity may be introduced into a polymer or composite system. One method is by coating the polymer with a conductive metal coating. A second method is the introduction of conductive additives such as metal or metal-coated powders or fibers into the polymer. Conventional additives include powders of metals such as silver, copper, nickel, iron and carbon, or fibers made of or coated with such metals. Another method is the creation of a conductive paint coating by adding metal powders or flakes to a paint, after which the paint may be used as a conductive coating.
In the case of composite materials, the reinforcing fibers may already be intrinsically conductive, such as is the case of carbon or metal-coated fibers. However, in the case of such composites, the conductivity is limited to the direction of the fibers. The adhesive polymer matrix of the composite insulates the fibers and greatly inhibits current flow in directions nonparallel to the fibers.
The poor electrical conductivity of such composite materials limits their usefulness in applications such as electromagnetic shielding, circuits, antennas, and the like. Furthermore, there are many applications in which known polymer-based composites may not be suitable because they do not sufficiently possess properties such as mechanical strength, thermal insulation, stiffness, and hardness. Known polymer-based composites may not be well suited to applications in which large, constant and/or repeated deflections occur, or applications in which deflection is to be measured.
Moreover, there are many applications in which it is desirable to coat an object with a conductive coating. It would be advantageous to enhance the electrical conductivity of such coatings for potential high-current applications such as electromagnetic shielding. Yet further, many applications require the use of objects with relatively complex shapes. Such complex shapes can be difficult or impossible to form from composite materials having the desired electrical conductivity.
Accordingly, it would be an advancement in the art to provide composite materials having increased thermal conductivity in comparison with the prior art. Furthermore, it would be an advancement in the art to provide conductive composite materials having a variety of additional characteristics such as mechanical strength, thermal insulation, stiffness, and hardness. Additionally, it would be an advancement in the art to provide conductive composite materials suitable for large deflection applications, and especially for deflection measurement. It would also be an advancement in the art to provide composite materials capable of being applied as highly conductive coatings. Yet further, it would be an advancement in the art to provide methods by which relatively complex, conductive composite shapes may be relatively easily and inexpensively manufactured.